EACH CAMERA IS SMALL ENOUGH to snugly fit into a breast pocket. It is tiny even in an underwater housing, so there is no excuse for not taking it on every dive.
The makers of modern digital snapshot cameras boast of their capacity to take close-up (macro) images, one of the most important features of any underwater camera.
Each has exceptional depth of focus, another important characteristic.
Each has a large and brilliant LCD screen, making image composition easy in murky waters.
Finally, each one can record video clips of decent quality. And all knobs and buttons needed to manage the camera settings are accessible even from outside the housing.

That's the good news, but the coin has a flip-side. In comparison with, say, a single lens reflex (SLR) camera in an underwater housing, the auto-focus mechanism on a compact may work disturbingly slowly.
Often a looooong while passes from the moment you press the trigger until the camera actually exposes the image.
The range of the flashgun is limited, yet at close-up distances the flashlight dominates too much.
The automatic white balance feature doesn't have the faintest idea of light conditions in water, certainly not in greenish, hazy northern waters.
The widest zoom lenses fail even to approach 'real' wide angle. The best give an angle of view corresponding to a 28mm lens on 35mm film. This is immediately transformed into 35mm in the housings available for the cameras tested here.
Underwater housings themselves are problematic. None of the tested cameras was neutrally buoyant, so don't let it slip in deep water - use the wrist strap.
The minuscule size of the housing means that all knobs and buttons have to be located very close together, so using gloves when setting the camera becomes an intricate procedure.
The icons for control functions are usually in the same colour as the housing - in other words transparent and so very hard to decipher, particularly in the bad light conditions in which you really need them.
If you are hoping to capture images of swimming fish, you should probably consider an SLR camera in an appropriate housing. With a compact you may get frustrated seeing fish after fish in the viewfinder, because either the camera will fail to focus on them or the fish will have vanished from the frame before the image has been recorded.
That said, with some practice and skills you can still capture quite good images with the cameras we test here, and document and portray friends and events on dive trips above the surface as well as below.
It's worth noting that while film cameras remained unchanged except for details for decades, by the time you read this the compact cameras reviewed may well have been replaced by newer models. These cameras are among the consumer durables that see continual upgrading to stimulate more sales.
If you buy the latest model today, its replacement may already have been despatched from the Far East.
This means that your camera has little value as a trade-in, so is not a stand-alone investment - you must use it to derive value from it.
With this quick turn-round, it's essential to buy the housing when you buy the camera, because you may have difficulty finding one later.
Buy a good camera and that is what you will always have, even if a later model has superceded it.

Each camera was set on automatic exposure as prescribed by the manufacturer and carefully inserted into its housing. We examined the ability of each model to set focus correctly in water, and then checked such test parameters as noise, sharpness, white balance and colour rendition.
The quality of the cameras was evaluated through images of a test board similar to those used to test computer screens and colour printers.
We laminated the board and mounted it on a piece of plywood to keep it flat, and the distance of the camera from the board was kept constant.
By comparing the images displayed on a carefully calibrated computer monitor against the test board itself, we were able to evaluate a number of test parameters:

  • Sharpness: How the many fine details and sharp contours on the test board are rendered reveals the camera's ability to focus correctly in water.
  • Dynamic range: If possible, the camera should render the grey scale on the upper part of the test board in its full length. The image should show a clear difference between the grey patches all the way to both ends of the scale.
  • Colour rendering: The test board carries a lot of details in red, yellow and other colours that
    are difficult to render in water. If at all possible, the camera should be able to render them correctly at the distance we used, at least with flash.
  • White balance: To the right of the grey scale is a white patch, which should be rendered as pure white on the images. The closer to pure white it is, the better the white balance. Large deviations from white indicate a camera's lack of ability to white-balance the ambient light,
    and the result will be a heavy colour cast (wrong colour correction) throughout the entire spectrum.

    Maximum depth for all the housings in the test was 40m, according to their specifications. Prices are for camera with housing included, the only exception being the Ewa-Marine bag-type housing, which has a maximum depth of 10m and is priced without camera.

    Price: ?380 (camera ?230, housing ?150), www.canon.co.uk, wetaccessories.net
    The housing is compact and feels both robust and delightful, almost like a piece of jewellery. Handling is simple. The extremely large screen makes it easy to navigate between different settings and programs.
    The camera has a special mode for underwater photography, but unfortunately it assumes that water is always blue. The big LCD screen is very pleasantto use, including as a viewfinder for composing images in murky water.
    In theory, the Macro mode is excellent, and the camera can focus down to 3cm, but the flash lacks the dexterity to expose correctly subjects that close. The result is massive over-exposure in these situations, with the highlighted parts of the images white and 'burned out' beyond rescue.
    We found the flash to be useful down to about 20cm from the subject, and if you go any closer it is advisable to turn the flash off.
    In any case, you have to go to shallow depths with better light conditions to get good close-up images.
    Automatic exposure was generally good and well balanced. White balance in water was ranked at the better end of the range among the tested cameras. The dynamic range was of average quality. Like the other housings, this one has a semi-translucent diffuser in front of the flash, which softens the light but reduces its range considerably.
    All the settings of the camera can be managed under water, though the control buttons are located within a very cramped space, making operation with gloves rather tricky.
    Resolution: 6 Megapixels
    ISO settings: 80-800
    Focus down to 30cm: In Macro mode 3cm
    Zoom (35mm equivalent): 35-105mm
    Shutter speeds: 15-1/1500 sec
    Memory type(s): SD/MMC
    Video/audio: Yes/yes

    Pros: Exceptionally large and brilliant screen
    Cons: Light from the flash too strong for close-up photography (a general problem with all the tested cameras).

    Price: £448 (the £249 FX01 has just been replaced by the £299 FX07, with housing ?149), www.panasonic.com

    Very compact and solid camera, with a lens made by Leica, which usually means high quality. It offers a wide-angle equivalent to 28mm on 35mm film, outstanding for such a small camera, and has a special mode for underwater photography, though only blue is corrected for, not green.
    Instead, you have the option to set the white balance manually. With manual balance you get natural colours but the images have a bit too much digital 'noise' at ISO settings between 200 and 400, especially in gloomy light conditions. Even higher ISO settings are possible but useless.
    Autofocus speed is good and the camera seems to work fast generally. It reacts immediately on new settings. Automatic exposure is acceptable and colour rendition very vivid. This becomes obvious when you compare red hues on the test board with images from the other cameras - red is truly red.
    The camera has a built-in image stabiliser. Blurred images caused by camera shake are not usually the worst problem under water but the stabiliser was excellent for close-up work.
    Like the other cameras, this one has difficulty in regulating flashlight strength close up to a subject.
    The solution was to turn off the flash, use ambient light and let the stabiliser do its job during the long exposure time.
    The underwater housing also seems to be well-built. All settings on the camera can be managed in the water, though again the controls are sited very close together, making handling with gloves tricky.
    Resolution: 6 Megapixels
    ISO settings: 80-400 (800-1600 with certain limitations)
    Focus down to 50cm: In Macro mode 5cm
    Zoom (35mm equivalent): 28-102mm
    Shutter speeds: 8-1/2000sec
    Memory type: SD/MMC
    Video/audio: Yes/yes

    Pros: Best and largest wide angle. Good close-up mode. Very long battery time.
    Cons: Camera unable to regulate flash strength close up. Too much digital noise at ISO 400, nearly useless at ISO 800 and 1600.

    Price: £348 (camera £199, housing ?149), www.fujifilm.co.uk, wetaccessories.net
    You can probably sell cameras by offering more pixels than your rivals, but Fujifilm has chosen a different path. Its philosophy is that the number of pixels should be 'sufficient' but that each and every pixel must deliver as high-quality output as possible. This camera gave the widest dynamic range in the test, the most natural colours, and sharpness surpassed only by the Nikon.
    The Finepix F30 offers ISO settings all the way up to 3200, which gives several advantages.
    Firstly, the camera successfully produces images where all the others are forced to give up due to insufficient light. Secondly, it can produce sharp images where the others give only smudge and blur, because it can use a shorter exposure time.
    Alternatively, you can use the flash. Digital compacts usually turn this on automatically when needed, though
    you will soon get fed up with images with an unnaturally bright foreground against a dark background. The range of the flash is only a metre or so.
    The digital noise in images taken at ISO 3200 is acceptable and you can do a lot at ISO 800, which produces images of impressive quality.
    Automatic focusing in water is reasonably fast and precise, and white balance can be set manually. Also, nearly all other camera settings can be manipulated in manual mode.
    Creative photographers are able to choose aperture and shutter speed for themselves.
    The camera has a special underwater mode, though this is not very impressive in greenish waters. The angle range of the zoom lens is equivalent to 36-112mm on an old-fashioned 35mm camera in air or 45-140mm in an underwater housing of this type.
    The housing is similar to the others in the test but with one very important difference - the control knobs and buttons are more widely spaced.

    Resolution: 6.1 Megapixels
    ISO settings: 100-3200
    Focus down to 60cm: In Macro mode 5cm
    Zoom (35mm equivalent): 36-112mm
    Shutter speeds: 15-1/2000sec
    Memory type: xD-card
    Video/audio: Yes/yes

    Pros: Probably the best digital compact camera on the market, judging from the image quality obtained. Nearly noiseless images at high ISO settings will enable you to do
    photography without flash in previously 'unthinkable' light situations. Long battery time.
    Cons: Image quality in water less impressive than in air.

    Price: £494 (camera £349, housing £145. The camera has just been discontinued pending a replacement but there should be plenty in stock at discount prices). www.nikon.co.uk, www.fantasea.com
    Small Mercedes cars usually 'inherit' luxury features from the big ones. In much the same way, this camera has been endowed with features from Nikon's famous professional models.
    It is the biggest camera in the test but still a neat little gadget. Compared with the other cameras, it feels a bit tawdry and has no special underwater mode, but the automatic white balance was the best in the entire test.
    Auto-exposure gives images that are slightly under-exposed. The dynamic range is medium.
    This camera produced the sharpest images of all the test models. It also has an excellent close-up (Macro) mode that focuses down to only 4cm. Regrettably you have to switch off the flash for close-up work, as on the other cameras, or stay at least 15-20cm from the subject.
    You can however take reasonably sharp images of immobile subjects really close up by using the built-in Vibration Reduction mode and ambient light only. With moving subjects, sharp images in close-up mode are impossible. The only option is move back and turn on the flash.
    In water, the auto-focus mechanism works slowly. Shutter delay seemed to be longer than with the other tested cameras. But valuable features include 'D-lighting' in the camera, an image-processing program designed to lighten shadows. This should be used with some caution, as noise will soon start to appear in the shadows.
    The underwater housing comes from the US manufacturer Fantasea, which specialises in underwater cases for a number of Nikon cameras, except for top-of-the-line professional models.
    The quality of this one is not quite on a par with that of other housings in the test, though from a practical point of view the difference is negligible. The camera controls were the most easily managed in the test.

    Resolution: 8 Megapixels
    ISO settings: 50-400
    Focus down to 30cm: In Macro mode 4cm
    Zoom (35mm equivalent): 36-126mm
    Shutter speeds: 8-1/2000sec
    Memory type: SD/MMC
    Video/audio: Yes/yes

    Pros: Best sharpness and resolution. Automatic white balance gave the most natural colours in the test. Generally good flash system, though with certain drawbacks.
    Cons: Flash problems in Macro mode. Noisy images at ISO 400.

    Price: £80, www.ewamarine.com, www.camerasunderwater.co.uk

    Ewa-Marine provides an option with high potential image quality but low user-friendliness. You insert your camera into a sturdy bag of transparent flexible PVC, which is closed by screwing two metal plates together, so remember to set the camera ready for action before you close the bag!
    Theoretically you can change any settings while it's in the bag, but in practice you will find it extremely difficult to do anything but press the trigger, particularly if you're wearing gloves. If that is enough for you, the Ewa-Marine bag will enable you to take underwater images at least as good as with any of the other considerably more expensive combinations of camera and housing.
    The D-SW model is rated for a maximum depth of 10m. This limit is imposed not by the danger of anything leaking or breaking at greater depth, it's just that water pressure will cause the bag to shrink, wrinkle and wrap itself snugly round the camera. Finally, it will press all the buttons on the camera simultaneously!
    We experienced how the camera lens was pressed tightly against the front port when we tried to activate the camera and got an error message before the camera shut itself down. Our Ewa-Marine bag was manufactured for exactly the camera we used, and the quality of the bag material is top class. We solved the problem by pulling the front port while re-starting the camera.
    Larger Ewa-Marine bags offer the option to add air and compensate for increasing pressure, so you can use the bag deeper and manage camera settings at greater depths.

    Pros: A comparatively cheap and simple way to take any camera with you in the water, as there are bags for virtually all makes, so it could be excellent for a snorkelling trip or the beach. Image quality is determined by the camera.
    Cons: Limited ability to manage camera settings, limited maximum depth.

    Water filters light selectively. Digital cameras can be adjusted to compensate for the deficiency of red light in the shallows, or you can add a reddish filter to reduce the amount of blue light to compensate. You can adjust the colour later on your PC, armed with suitable software.
    However, if there is no red or yellow light at your depth, you cannot simply make an adjustment to put it back. You need to take an auxiliary light to give a full spectrum of colour, which means using a very bright HID lamp or an ancillary flashgun.
    The built-in flash is never very bright and is usually positioned too close to the optical axis of the lens, so that it will tend to light up detritus in the water, often known as 'backscatter'. The built-in flash can be used to trigger an external flash, using a fibre-optic connection, but it should be blanked off so that its light does not affect the picture. Ancillary flash could almost double the cost of your camera.